Table Of Content

Agriculture, Ecosystems and Environment, 37 (1991) 333-334 Elsevier Science Publishers B.V., Amsterdam Contents of Agriculture, Ecosystems and Environment, Volume 37 Vol. 37 Nos. 1-3 October 1991 Special Issue: Biological control of weeds in South Africa Introduction J.R. Hoffmann (Rondebosch, South Africa ) Biological control of jointed cactus, Opuntia aurantiaca (Cactaceae) , in South Africa V.C. Moran (Rondebosch, South Africa) and H.G. Zimmermann (Pretoria, South Africa) Biological control of prickly pear, Opuntia ficus-indica (Cactaceae ), in South Africa H.G. Zimmermann (Pretoria, South Africa) and V.C. Moran (Rondebosch, South Africa) Biological control of cactus weeds of minor importance in South Africa V.C. Moran (Rondebosch, South Africa) and H.G. Zimmermann (Pretoria, South Africa) Biological control of Lantana camara (Verbenaceae) in South Africa C.J. Cilliers and S. Neser (Pretoria, South Africa) Biological control of St. John’s Wort, Hypericum perforatum (Clusiaceae ), in South Africa A.J. Gordon (Stellenbosch, South Africa) and R.L. Kluge (Pietermaritzburg, South Africa ) Biological control of Hakea sericea (Proteaceae ) in South Africa R.L. Kluge (Pietermaritzburg, South Africa) and S. Neser (Pretoria, South Africa) Biological control of Acacia longifolia and related weed species (Fabaceae) in South Africa G.B. Dennill (Pretoria, South Africa) and D. Donnelly (Stellenbosch, South Africa) .... Biological control of silverleaf nightshade, Solanum elaeagnifolium, and bugweed, Solanum mauritianum, (Solanaceae ) in South Africa T. Olckers (Uitenhage, South Africa) and H.G. Zimmermann (Pretoria, South Biological control of Sesbania punicea (Fabaceae) in South Africa J.H. Hoffmann and V.C. Moran (Rondebosch, South Africa) Biological control of mesquite, Prosopis spp. (Fabaceae), in South Africa H.G. Zimmermann (Pretoria, South Africa ) Biological control of crofton weed, Ageratina adenophora (Asteraceae) , in South Africa R.L. Kluge (Pietermaritzburg, South Africa ) Biological control of triffid weed, Chromolaena odorata (Asteraceae), in South Africa R.L. Kluge (Pietermaritzburg, South Africa) 334 Biological control of spear thistle, Cirsium vulgare (Asteraceae) , in South Africa H.G. Zimmermann (Pretoria, South Africa) Biological control of water hyacinth, Eichhornia crassipes (Pontederiaceae ), in South Africa C.J. Cilliers (Pretoria, South Africa ) Biological control of water fern, Sa/vinia molesta (Salviniaceae ), in South Africa C.J. Cilliers (Pretoria, South Africa) Biological control of water lettuce, Pistia stratiotes (Araceae), in South Africa C.J. Cilliers (Pretoria, South Africa ) Biological control of fennel-leaved pondweed, Potamogeton pectinatus (Potamogetonaceae ), in South Africa H.J. Schoonbee (Johannesburg, South Africa ) The use of plant pathogens for biological weed control in South Africa M.J. Morris (Stellenbosch, South Africa) The Guide for Authors will appear in Volume 37 No. 4 Vol. 37 No. 4 November 1991 Fluoride content in grass as related to atmospheric fluoride concentrations: a simplified predictive model L.J. van der Eerden (Wageningen, Netherlands) A model describing the influence of hard seededness on the persistence of an annual forage legume, in a ley farming system, in a mediterranean-type environment G.B. Taylor, R.A. Maller and R.C. Rossiter (Wembley, W.A., Australia) Leaching and runoff losses of herbicides in a tilled and untilled field J.K. Hali, RO. Mumma and D.W. Watts (University Park, PA, USA) Book Reviews Soil Degradation The Greenhouse Effect Agroecology Whiteflies ne h‘ e Scoatn3ue e aa eh y